This invention relates to automatic milking apparatus.
Automatic milking apparatus includes, for each cow milking unit, a clawpiece and a cluster of four teat cups connected to the clawpiece. Each teat cup has a rigid shell and an internal flexible liner. This liner has a topmost mouthpiece diaphragm with a circular mouthpiece and a body part inside the shell body. The liner extends through the bottom of the shell body as a short milk tube. This tube is connected to the clawpiece and thence, by way of a long milk tube, to a source of steady vacuum.
An annular space, between the teat cup shell and the teat cup liner, is connected to the clawpiece by a pulse tube and thence to a source of pulsating vacuum.
For milking, the four teat cups are placed around the cow's teats, the liner mouthpiece of each teat cup being fitted over the respective teat. The teat cups are held in position during the milking operation by adhesion, due to the steady vacuum applied for the milking operation. The pulsating vacuum applied between the teat cup liner and shell causes the liner body to dilate and contract again, thus promoting the flow of milk by simulating suckling. After completion of the milking operation, the teat cup cluster is removed from the cow's teats, either manually or by automatic means.
In milking methods which are conventional at the present date, in which a continuous air bleed is provided at the clawpiece or upstream of the clawpiece, the steady vacuum induced adhesion is automatically broken when the vacuum supply is shut off at the end of milking, so that the teat cup cluster is easily removed from the milked cow.
However, a more modern milking method, known as the hydraulic milking method, has recently been introduced. In this hydraulic milking method there is no air bleed at or upstream of the clawpiece during milking, that is to say during the process of drawing milk from an individual cow. In consequence, the steady vacuum induced adhesion of the teat cup liner to the cow's teat is not broken when the vacuum supply is shut off after milking. Some other means is thus needed to break the vacuum adhesion before the teat cups can easily be removed from the milked cow.
It has been proposed, in co-pending patent application U.S. Pat. No. 8520814, to groove the surface of the teat cup liner mouthpiece, in the area where it makes contact with the surface of the cow's teat, so that, upon the displacement caused by a downward pull on the teat cup, the contact seal is broken and air is admitted around the mouthpiece, past the teat and into the liner body, thereby permitting of easy removal of the teat cup.
It has been proposed, in co-pending patent application U.S. Pat. No. 8603302, to provide one or more apertures in the mouthpiece diaphragm, each aperture having a closure stop which closes the aperture as the teat cup is fitted and opens as the teat cup is removed.
The object of the present invention is to provide automatic milking apparatus, particularly the teat cup and clawpiece components thereof, in which air may be admitted positively into the body space of the teat cup liner, at will upon the completion of the milking operation.
Accordingly, the present invention provides for automatic milking apparatus, a teat cup liner of elastomeric material having a topmost mouthpiece, a downwardly extending body part, for fitting within a teat cup rigid shell, and a tubular extension below the body part, forming a short milk tube for connection to a clawpiece, the body part of the teat cup liner having a passage therethrough providing an opening into the body interior, below the mouthpiece of the teat cup liner, whereby air may be admitted into the said body interior, at will.
The invention further provides, for automatic milking apparatus, a teat cup having a liner as described in the last preceding paragraph, fitted within a rigid shell, said shell providing for the connection of a pulse tube with the space between the liner body and the shell body, said liner passage providing for the connection of an air admission tube therewith, the air admission tube extending within the space between the liner body and the shell body and extending out of the shell inside the pulse tube.
The invention further provides, for automatic milking apparatus, a cluster of four teat cups, each as described in the last preceding paragraph, in combination with a clawpiece, said clawpiece having a pulsation block and milk flow parts, each of said teat cups having the pulse tube thereof connected to a connector of the pulsation block and having the said air admission tube within the pulse tube thereof connected to an air-flow connector provided by said clawpiece, each of said teat cups having the short milk tube extension of the teat cup liner thereof connected to a connector of the milk flow part of said clawpiece, said clawpiece further having a movable control member connected to a steady vacuum and milk flow control valve within said milk flow part of said clawpiece, and an air-inlet valve, controlling air-flow from atmosphere to the air-flow connector, being linked to the said control member, said air-inlet valve being closed when the steady vacuum and milk flow control valve is open and being open when the steady vacuum and milk flow control valve is closed.
The invention further provides methods of automatic milking consequent upon the use of the apparatus defined in the preceding paragraphs. Thus, the invention provides a method of automatic milking by which there is no air bleed at or upstream of the clawpiece during milking and, after milking and before the removal of teat cups from a cow's teats, air is admitted to the interior of the bodies of the teat cup liners by way of a passage through each liner body, between the interior and exterior thereof, and by way of an air admission passage connected to the liner body passage.